Journal of Magnetism and Magnetic Materials, Mar 1, 2012
ABSTRACT The deformation of the free surface of a magnetic fluid containing a cylinder made of a ... more ABSTRACT The deformation of the free surface of a magnetic fluid containing a cylinder made of a magnetizable material subjected to a uniform applied magnetic field is analyzed. The statics and dynamics of a magnetic fluid free surface is studied theoretically and experimentally. A discontinuous (jump-like) change of the surface shape is shown to occur when the applied magnetic field gradually increases or decreases. If the applied magnetic field increases and then decreases, a hysteresis of the shape is observed.
... de Dr. Carsten Behn TU Ilmenau Fakult¨at f¨ur Maschinenbau FG Technische Mechanik PSF 100565 ... more ... de Dr. Carsten Behn TU Ilmenau Fakult¨at f¨ur Maschinenbau FG Technische Mechanik PSF 100565 98684 Ilmenau/Germany carsten.behn@tu ... Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9 ...
The paper deals with a spherical pendulum inside a spherical ferrofluid volume in the presence of... more The paper deals with a spherical pendulum inside a spherical ferrofluid volume in the presence of an uniform magnetic field. The problem is motivated by biological tactile sensors of mammals. These thin long hairs, called vibrissae, grow from a special follicle incorporating a capsule of blood and are used by mammals for exploration of the surrounding area. We propose a continuum model of the viscoelastic support of a vibrissa inside the follicle as a spherical volume filled with ferrofluid. It is a stable colloidal suspension of nanoscale ferromagnetic particles in a viscous carrier liquid. The tactile hair is modeled as a rigid rod with a spherical body at the end, which is submerged inside the ferrofluid. Using analytic expressions for the magnetic force acting on a paramagnetic body in the presence of an uniform magnetic field, Euler’s equations of motion of the spherical pendulum are derived. The conditions for the maximum possible magnitude of the magnetic force acting on the body are analyzed. It is shown that the dynamical behavior of the pendulum may be controlled by means of an uniform applied magnetic field. The results are important for the development of artificial tactile sensors.
Mechanical systems that consist of a four-wheeled or two-wheeled robot with Mecanum wheels and a ... more Mechanical systems that consist of a four-wheeled or two-wheeled robot with Mecanum wheels and a two-wheeled trailer with conventional wheels are considered. The kinematic characteristics of the mechanical systems under consideration of holonomic and non-holonomic constraints are presented and compared. From this, it is shown that the structure of the kinematic constraint equations for mobile systems with a trailer does not apply to Chaplygin’s dynamic equations. If the mechanical system is not Chaplygin’s system, then the dynamic equations cannot be integrated separately from the equations of kinematic constraints. This is the difference between the kinematic constraint equations for the robot-trailer system and the constraint equations for a single robot with Mecanum wheels. Examples of numerical calculations using the equations of kinematic constraints are given.
Advances on Theory and Practice of Robots and Manipulators, 2014
A two-module (two-body) locomotion system moving along a straight line on a rough horizontal plan... more A two-module (two-body) locomotion system moving along a straight line on a rough horizontal plane is considered. The motion of the system is excited by a periodic change in the distance between the bodies. Friction between the bodies and the plane obeys Coulomb’s law. The conditions for the system to be able to start moving from a state of rest and the steady-state motion are studied. The friction force acting on the system is assumed to be small as compared with the excitation force, and the method of averaging is applied to the equation of motion of the system’s center of mass. On the basis of the averaged equation, necessary and sufficient conditions subject to which the system can start moving from a state of rest in a dry friction environment are obtained. The excitation law that implies a piecewise quadratic time history of the distance between the bodies is considered. For this excitation law, the system can start moving from a state of rest if the bodies have different masses and the times of increase and decrease of the distance between them do not coincide. Closed-form expressions for the steady-state velocity of the system’s center of mass are obtained and investigated as a function of the parameters of the system and the excitation law. The maximum magnitudes of the steady-state velocities and the respective values of the parameters are found. An experimental prototype of the robot under consideration was built. The experimental results demonstrate qualitative agreement with the theoretical predictions.
Journal of Magnetism and Magnetic Materials, Mar 1, 2012
ABSTRACT The deformation of the free surface of a magnetic fluid containing a cylinder made of a ... more ABSTRACT The deformation of the free surface of a magnetic fluid containing a cylinder made of a magnetizable material subjected to a uniform applied magnetic field is analyzed. The statics and dynamics of a magnetic fluid free surface is studied theoretically and experimentally. A discontinuous (jump-like) change of the surface shape is shown to occur when the applied magnetic field gradually increases or decreases. If the applied magnetic field increases and then decreases, a hysteresis of the shape is observed.
... de Dr. Carsten Behn TU Ilmenau Fakult¨at f¨ur Maschinenbau FG Technische Mechanik PSF 100565 ... more ... de Dr. Carsten Behn TU Ilmenau Fakult¨at f¨ur Maschinenbau FG Technische Mechanik PSF 100565 98684 Ilmenau/Germany carsten.behn@tu ... Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9 ...
The paper deals with a spherical pendulum inside a spherical ferrofluid volume in the presence of... more The paper deals with a spherical pendulum inside a spherical ferrofluid volume in the presence of an uniform magnetic field. The problem is motivated by biological tactile sensors of mammals. These thin long hairs, called vibrissae, grow from a special follicle incorporating a capsule of blood and are used by mammals for exploration of the surrounding area. We propose a continuum model of the viscoelastic support of a vibrissa inside the follicle as a spherical volume filled with ferrofluid. It is a stable colloidal suspension of nanoscale ferromagnetic particles in a viscous carrier liquid. The tactile hair is modeled as a rigid rod with a spherical body at the end, which is submerged inside the ferrofluid. Using analytic expressions for the magnetic force acting on a paramagnetic body in the presence of an uniform magnetic field, Euler’s equations of motion of the spherical pendulum are derived. The conditions for the maximum possible magnitude of the magnetic force acting on the body are analyzed. It is shown that the dynamical behavior of the pendulum may be controlled by means of an uniform applied magnetic field. The results are important for the development of artificial tactile sensors.
Mechanical systems that consist of a four-wheeled or two-wheeled robot with Mecanum wheels and a ... more Mechanical systems that consist of a four-wheeled or two-wheeled robot with Mecanum wheels and a two-wheeled trailer with conventional wheels are considered. The kinematic characteristics of the mechanical systems under consideration of holonomic and non-holonomic constraints are presented and compared. From this, it is shown that the structure of the kinematic constraint equations for mobile systems with a trailer does not apply to Chaplygin’s dynamic equations. If the mechanical system is not Chaplygin’s system, then the dynamic equations cannot be integrated separately from the equations of kinematic constraints. This is the difference between the kinematic constraint equations for the robot-trailer system and the constraint equations for a single robot with Mecanum wheels. Examples of numerical calculations using the equations of kinematic constraints are given.
Advances on Theory and Practice of Robots and Manipulators, 2014
A two-module (two-body) locomotion system moving along a straight line on a rough horizontal plan... more A two-module (two-body) locomotion system moving along a straight line on a rough horizontal plane is considered. The motion of the system is excited by a periodic change in the distance between the bodies. Friction between the bodies and the plane obeys Coulomb’s law. The conditions for the system to be able to start moving from a state of rest and the steady-state motion are studied. The friction force acting on the system is assumed to be small as compared with the excitation force, and the method of averaging is applied to the equation of motion of the system’s center of mass. On the basis of the averaged equation, necessary and sufficient conditions subject to which the system can start moving from a state of rest in a dry friction environment are obtained. The excitation law that implies a piecewise quadratic time history of the distance between the bodies is considered. For this excitation law, the system can start moving from a state of rest if the bodies have different masses and the times of increase and decrease of the distance between them do not coincide. Closed-form expressions for the steady-state velocity of the system’s center of mass are obtained and investigated as a function of the parameters of the system and the excitation law. The maximum magnitudes of the steady-state velocities and the respective values of the parameters are found. An experimental prototype of the robot under consideration was built. The experimental results demonstrate qualitative agreement with the theoretical predictions.
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Papers by Igor Zeidis